This invention relates in general to takeoff and landing platforms for V/STOL airplanes, for reducing undesirable ground effect.
Vertical and short takeoff and landing airplanes are known as "V/STOL" airplanes. Normally, a V/STOL airplane has jet engines with nozzles that will deflect downwardly for takeoff and landing. A V/STOL airplane experiences undesirable ground effect during the takeoff and landing. The hot high velocity jet exhaust gas streams striking the landing surface create a suckdown force, reducing lift. Another effect, known as "fountain", results in an upward force on the aircraft. The fountain can be disadvantageous, also, since the positioning of the fountain is difficult to control. Also, the hot, upwardly deflected gasses if ingested by the engine inlet(s) will reduce the efficiency of the engine(s). Consequently, it is normally desirable to minimize such ground effects.
Some prior art proposals employ blades or vanes in a platform mounted above the underlying horizontal surface or ground plane and positioned to intercept exhaust gases from the engine and turn them so they are discharged away from the plane. e.g., laterally. Some of these proposals are complex, requiring spring loaded check valves or locating the vanes higher than desired above the ground plane, e.g., for shipboard use. Others utilize relatively small platforms, one for each jet stream or have constructions requiring rather precise positioning of the aircraft with respect to the blades during takeoff and landing to properly direct the engine exhaust.